Studies are in progress to define regorously a putative new genetic type of elastin isolated in our laboratory from elastic cartilage. In order to facilitate these studies, development of new oxidative protein side-chain degradative reactions are under investigation in order to facilitate the controlled and defined solubilization and degradation of various elastins and collagens. Investigations are also in progress on the mechanism of the microsomal vitamin K-dependent protein carboxylation reaction. This reaction, leading to the formation of gamma-carboxyglutamic acid residues from glutamic acid residues, is a O2, CO2 dependent mixed function oxidative-carboxylative reaction. Model heterogeneous organic chemical systems have been set up to study the chemical features and mechanism of this new type of reaction.